Ceratrichia (Butler 1870a)

Larsen, Torben B., 2013, Ceratricula and Flandria — two new genera of Afrotropical Hesperiidae (Hesperiinae (incertae sedis )) for species currently placed in the genus Ceratrichia Butler, Zootaxa 3666 (4), pp. 476-488 : 476-478

The genus Ceratrichia (Butler 1870a)

The Ceratrichia form a large genus (20 species or so) of small skippers that are found in the evergreen forests of Africa from the Basse Casamance in Senegal to the Albertine Rift area in Kivu, Uganda, western Kenya, western Tanzania, and western Zambia. A single somewhat special species ( C. bonga Evans ) lives in isolation from other member of the genus in the coastal forest vegetation of northeastern Tanzania. Superficially they fall into four distinct groups with surprisingly different colour patterns (figure 1):

1) C. flava -group with bright yellow forewings having dark forewing margins and bright yellow hindwings with a dark apical patch (4–5 species).

2) C. phocion -group with black forewings having none or a variable number of small white hyaline spots, while the hindwings are yellow with a black costa, the black colour intruding into the base and cell (9 species).

3) C. nothus -group with both wings blackish above, mostly with small white hyaline spots, and with more than half the underside white (2–3 species).

4) C. argyrosticta -group with large ochreous or yellow spots on the forewings, some of which hyaline, and larger annulated pearly spots on the hindwing underside (5–6 species).

Some of the species are currently treated as subspecies and one or two need eventually to be described.

Irrespective of their colour patterns, members of the genus are characterized by:

a) the unusually long antennae, five-eighths the length of the forewing costa, the longest amongst the African Hesperiidae .

b) the palps with the second segment erect and the third very short, porrect.

c) the origin of vein 2 being equidistant between the wing base and the end of the cell.

d) the very special spotting pattern in the forewing subapical area with the spot in 6 shifted far inwards (except in the C. argyrosticta -group).

e) the postdiscal hindwing underside spotting consisting of small brown circles with yellow, white, or pearly centres (annulated), a feature accentuated in the C. argyrosticta -group.

f) the distinctive genitalia structure differing from all other African Hesperiidae as described below and illustrated in figure 2.

The genitalia of the Ceratrichia are so distinctive that any member of the genus can immediately be recognized as such by the genitalia alone. I have now dissected and/or obtained slides of all known or putative taxa within the genus (about 100 slides in all). Figure 2 shows the genitalia of the species illustrating each of the four pattern groups in figure 1 above. Though the genitalia are all very similar, there are mostly sufficient minor differences in their exact shape and the relative proportions of their various components to tell them apart by the genitalia.

The tegumen has no special features and merges with an uncus that tapers to a single point. Any fenestrula is modest. The tip of the uncus is upturned, which is unusual, in one case pointing up almost vertically. The gnathos is poorly developed, being composed mostly of transparent membranes, usually with a slight support stem from the tegumen, and embracing a faint scaphium through which the anus runs (so weak that it is difficult to illustrate in scans). The valves are more or less quadrate except that the distal end of the cucullus is curved to a varying degree as it turns up to terminate as a more-or-less pointed triangular tip (only C. bonga has this tip rounded). There is a visibly weakly chitinized area between the dorsal edge of the valve and the cucullus. The cucullus is unusually smooth; there is no serration except in a few cases along the inner edge of the distal, dorsal thorn and hardly any hairs, and the texture is glossy. The penis is short but unusually broad, at its distal end often as wide as the valve itself (figure 2).

When beginning my study of the group I had expected to find the genitalia of the Ceratrichia argyrosticta - group to differ materially from the rest, but was surprised to find them consistent with other species in what is evidently a structurally homogenous genus, where the colour patterns differ much more strongly than the genitalia.

From this analysis it became clear that two species-groups currently included in Ceratrichia in no way conform with the genus, except for a vague superficial similarity with the C. phocion -group of no taxonomic value: one is Ceratrichia semilutea (Mabille 1891) and its subspecies; the other is Ceratrichia flandria (Evans 1956) , with its close relatives C. kelembaensis (Strand 1918) and C. weberi (Miller 1964) . These two groups are very different from true Ceratrichia with which they are not closely related; they are also not closely related to each other. Neither can be retained in Ceratrichia : their genitalia are structurally very different, the subapical spotting on the forewing underside does not conform, and the ornamentation on the hindwing underside does not include the characteristic annulated postdiscal spotting. Two new genera, Ceratricula and Flandria , are therefore described below to receive these species.

Figures

FIGURE 2. The male genitalia of the four Ceratrichia species illustrated in figure 1: 1. C. flava - group (C. wollastoni Uganda, Bwindi (tbl BKE )); 2. C. phocion - group (C. phocion Sierra Leone, Banta (mrac H. 602 )); 3. C. nothus - group (C. brunnea Uganda, Kigezi (mrac H. 144 )); 4. C. argyrosticta - group (C. aurea DRC, Kapanga (mrac H. 145 )).